Heart valve delivery system

ABSTRACT

A delivery system for delivering a prosthetic heart valve to a native valve site within the human vasculature. The prosthetic valve is disposed on a balloon at the end of a balloon catheter. The balloon catheter passes through a delivery sleeve assembly and handle. A pull wire travels from the handle to a distal end of the delivery sleeve assembly. Actuation of the handle pulls on the pull wire, which causes openings in a slotted tube of the delivery sleeve assembly to close, thus causing the delivery sleeve assembly to bend. A stretchable cover is placed over the slotted tube for biasing the steerable catheter toward a straight position. Once advanced to the native valve site, the prosthetic valve is deployed by inflating the balloon.

BACKGROUND OF THE INVENTION

The present invention relates to systems used to deliver a prostheticvalve to a heart. More specifically, the present invention is directedto an improved steerable delivery system for delivery of a prostheticvalve to a human heart.

Catheters are known in the art and have been commonly used to reachlocations inside the body that are not readily accessible by surgery orwhere access without surgery is desirable. The usefulness of cathetersis largely limited by the ability of the catheter to successfullynavigate through small vessels and around tight bends, such as aroundthe aortic arch.

Over the years, a variety of steerable catheters have been proposed forfacilitating navigation through difficult vasculature. For example, someknown devices employ a series of connected segments, each comprising ashape which allows the catheter to form a bent configuration adaptableto fit the particular need. The use of many connected segments, however,is complicated and costly.

Also known in the art is a device wherein portions have been removedfrom a hollow stylet wire, thus allowing the hollow wire to bend inareas where portions have been removed. However, known devices of thistype are used as stylets and have not been adapted for use in asteerable catheter.

Also known in the art is a device wherein spring bands are employed intoa steerable catheter, wherein one spring band has a natural curvatureopposite that of the direction of the bending of the device, thusproviding stability to the device. However, these bands add unnecessarycomplexity to the device and are therefore undesirable for many uses.

Although a variety of bendable and steerable devices have been proposedover the years, each of the existing devices has shortcomings that limitits effectiveness. Accordingly, an urgent need exists for an improvedsteerable delivery system to facilitate advancement of an implant and/ortherapy device through a patient's vasculature to a treatment site. Itis desirable that such a system overcomes the shortcomings associatedwith existing devices. It is also desirable that such a system beversatile, reliable and easy to use. The present invention addressesthis need.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a heart valvedelivery system for delivery of a prosthetic (i.e., replacement) heartvalve to a native valve site within the human vasculature. The deliverysystem includes a delivery sleeve assembly having a steerable sectionfor facilitating navigation around bends. The system is well suited foradvancing a prosthetic valve through the aorta (i.e., in a retrogradeapproach) for replacing a stenotic aortic valve.

In one preferred embodiment, the heart valve delivery system comprises atubular sleeve, a selectively steerable section coupled to a distal endof the sleeve, an elongate balloon catheter extending through the sleeveand steerable section, and a prosthetic valve disposed over anexpandable balloon along a distal end portion of the elongate ballooncatheter. The sleeve, steerable section, balloon catheter and prostheticvalve are configured for advancement as a single unit through apatient's vasculature. During advancement, the prosthetic valve islocated adjacent to a distal end portion of the steerable section andmay be advanced therefrom if desired.

In one variation, the sleeve of the heart valve delivery systemcomprises first and second outer lumens extending along a side of thesleeve. A pull wire passes through the first outer lumen, through thesteerable section to the distal end portion of the steerable section,and returns through the steerable section and through the second outerlumen. The pull wire is preferably actuated by a rotational handleassembly, wherein the rotational handle assembly is located proximal tothe sleeve.

In another variation, the steerable section comprises a slotted tubehaving a first straight position and a second curved position. Thesteerable section may be formed, at least in part, of a stainless steelhypotube. In one preferred embodiment, the sleeve is formed of apolyether block amide, known as Pebax®, and comprises a soft durometerPebax® near a distal end thereof.

The prosthetic valve may be located distal to the steerable section suchthat the distal end portion of the steerable section abuts a proximalend of the prosthetic valve. Alternatively, a shroud may be coupled tothe distal end portion of the steerable section. The shroud surrounds atleast a portion of the prosthetic valve during advancement through thepatient's vasculature.

In another embodiment, a heart valve delivery system comprises adelivery sleeve assembly having a main lumen, a slotted tube forming asteerable section of the delivery sleeve assembly, the steerable sectionhaving a first configuration wherein the steerable section issubstantially straight and a second configuration wherein the steerablesection is curved. The steerable section is enveloped by a covering,wherein the covering is stretchable such that it biases the steerablesection from the second configuration to the first configuration. Anelongate balloon catheter extends through the main lumen of the deliverysleeve assembly and a prosthetic valve is mounted to a balloon locatedat a distal end of the balloon catheter. The steerable section ispreferably acted upon by a pull wire which is actuated by a rotatorhandle which is mounted to a proximal end of the delivery sleeveassembly. The covering is preferably formed with a soft durometerpolyether block amide known as Pebax®. The sleeve is preferably formedof a polyether block amide and comprises a soft durometer polyetherblock amide near a distal end thereof.

In another embodiment, a method of delivering a prosthetic valve to anative valve site of a patient involves disposing a prosthetic valveover a balloon on a balloon catheter and placing the balloon catheterinside a delivery sleeve assembly having a steerable section which isactuated by a pull wire running along the length of the delivery sleeveassembly and attached to a moving member of a handle. The prostheticvalve is advanced to the native valve site by pushing the valve throughiliac and femoral arteries of the patient, over an aortic arch, and tothe native valve site, whereby the moving member pulls the pull wirewhen the handle is rotated in a first direction, causing the steerablesection to bend, and whereby the moving member releases the pull wirewhen the handle is rotated in a second direction, allowing the rigidityof the delivery sleeve assembly to straighten the steerable section.After reaching the native valve site, the balloon is inflated to deploythe prosthetic valve.

In one variation, the prosthetic valve is pushed through stenoticleaflets of an aortic valve site while the steerable section is bent. Inanother variation, the balloon catheter is distally advanced relative tothe delivery sleeve assembly until the prosthetic valve is locatedwithin the native valve site. The prosthetic valve preferably comprisesa stent portion supporting a valve structure. Because the deliverysleeve assembly provides steerability, an outer surface of the stent maybe substantially exposed during advancement over the aortic arch withoutdamaging the aorta. For enhanced pushability, a distal end of thesteerable section preferably abuts a proximal end of the stent portionwhile advancing the prosthetic valve to the native valve site.

In yet another embodiment, a method of delivering a prosthetic valve toa native valve site comprises disposing an expandable prosthetic valveover a balloon along a distal end portion of a balloon catheter, placingthe balloon catheter inside a delivery sleeve assembly having asteerable section which is actuated by a pull wire and advancing theprosthetic valve and delivery sleeve assembly toward the native valvesite substantially as a single unit while selectively adjusting thecurvature of the steerable section to facilitate advancement. When theprosthetic valve is advanced using a retrograde approach (i.e., over theaortic arch), the prosthetic valve may be advanced out of the deliverysleeve assembly after navigating the aortic arch. More particularly, theprosthetic valve may be advanced from the delivery sleeve assembly intothe native valve site. The balloon is inflated for deploying theexpandable prosthetic valve.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become appreciatedas the same become better understood with reference to thespecification, claims, and appended drawings wherein:

FIG. 1 is a side view of the heart valve delivery system delivering aheart valve to a native valve site according one preferred embodiment ofthe present invention;

FIG. 2 is a cross sectional view of a handle used in the deliverysystem;

FIGS. 3A and 3B are perspective and cross sectional views, respectively,of a first core member which forms a portion of the handle;

FIGS. 4A and 4B are perspective and cross sectional view, respectively,of a partially threaded member which is disposed around the core member;

FIGS. 5A and 5B are side and cross sectional views, respectively, of arotator handle;

FIGS. 6A and 6B are perspective and cross sectional views, respectively,of a second core member which forms another portion of the handle;

FIGS. 7A and 7B are perspective and cross sectional views, respectively,of a hub which is disposed around the second core member;

FIG. 8 is a side view of a guide tube having a passageway for slidablyreceiving a pull wire;

FIG. 9 is a perspective view of a sleeve formed with a central lumen;

FIG. 10 is a cross sectional view of a distal portion of a deliverysleeve assembly;

FIG. 11 is a side view of a flex tube which provides a steerablesection, wherein the flex tube has been laid flat for purposes ofillustration;

FIG. 12 is a cross sectional view of a portion of a delivery sleeveassembly according to an alternative embodiment;

FIG. 13 is a cross sectional view of a shroud section of the deliverysleeve assembly;

FIGS. 14A and 14B are perspective and cross sectional views,respectively, of a shroud which forms a portion of the shroud section ofFIG. 13;

FIGS. 15A, 15B, and 15C are perspective, cross sectional, and bottomviews, respectively, of a ring which forms a portion of the shroudsection of FIG. 13;

FIG. 16 is a cross sectional view of a balloon catheter configured foruse with the heart valve delivery system;

FIGS. 17A and 17B are perspective and cross sectional views,respectively, of a balloon which forms a portion of the balloon catheterof FIG. 16;

FIGS. 18A and 18B are cross sectional views of a distal end of thedelivery system, wherein FIG. 18A illustrates a first embodiment withthe prosthetic heart valve disposed distal to the shroud and FIG. 18Bshows a second embodiment with the prosthetic heart valve disposedwithin the shroud;

FIG. 19 is a side view of an introducer sheath assembly;

FIG. 20 is an exploded perspective view of a loader assembly used forloading the balloon catheter and prosthetic valve into the introducersheath assembly;

FIGS. 21A and 21B are side views illustrating the insertion of thedelivery system into the loader assembly;

FIG. 22 is a side view illustrating the relationship between thedelivery system, the introducer sheath assembly, and the loaderassembly; and

FIG. 23 is a side view of the delivery system during use, showingdeployment of the prosthetic heart valve at the native valve site forreplacing the function of a defective native valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference now to FIG. 1, for purposes of illustration, onepreferred embodiment of a heart valve delivery system 10 for deliveringa prosthetic valve 11 to a diseased aortic valve 12 of a human heart isshown. The delivery system is well-suited for delivering the prostheticvalve 11 through a patient's vasculature and over an aortic arch 13 to alocation adjacent the diseased valve 12.

The delivery system 10 generally includes a guide wire 14 and a ballooncatheter 15 configured for advancement over the guide wire 14. Theprosthetic valve 11 is provided along the distal end portion of theballoon catheter. The balloon catheter 15 includes a tubular section 16and a handle/support 17 at a proximal end of the tubular section 16. Thetubular section 16 of the balloon catheter 15 is received within adelivery sleeve assembly 18. The delivery sleeve assembly generallycomprises a sleeve 19, a steerable section 20 and a shroud section 21. Aproximal end of the delivery sleeve assembly 18 is mounted to a handle22. The delivery system 10 passes through an introducer sheath assembly400 and a loader assembly 500, both of which will be described in moredetail below, to enter the body vessel and deliver the valve 11.

With reference to FIG. 2, the handle 22 at the proximal end of thedelivery sleeve assembly 18 generally includes an end cap 23, anadjustable portion 24, and a hemostasis portion 25. The adjustableportion 24 includes a first core member 26, a partially threaded member27 around the first core member 26, and a rotator handle 28 around thepartially threaded member 27. The hemostasis portion 25 includes asecond core member 29 and a hub 30 around the second core member 29. Ahemostasis tube 31 extends outwards from the hub 30. A guide tube 32 isplaced within the handle 22 as will be described in greater detailbelow.

With reference to FIGS. 3A and 3B, the first core member 26 is generallytube shaped having a passageway 33 extending longitudinallytherethrough. An annular flange 34 forms a proximal end 36 of the firstcore member 26. A first slot opening 38 allows communication from theouter surface of the first core member 26 into the passageway 33, andalong a length of the first core member 26. A second slot 40 travelsalong the length of the outer surface of the first core member 26 from adistal end 42 towards the flange 34. The flange 34 includes a firstfastener opening 44 extending radially from the outer surface of thefirst core member 26. A longitudinally extending access opening 46 at aproximal end of the slot 40 extends from a proximal end wall 47 of theslot 40 into the first fastener opening 44.

With reference to FIGS. 4A and 4B, the partially threaded member 27 hasa proximal end 48 and a distal end 50. The partially threaded member 27is generally tube shaped having a passageway 52 extending longitudinallytherethrough. Toward the proximal end 48, the outer surface of thepartially threaded member 27 has an exterior thread 54. The thread 54includes a radially extending dowel opening 56 extending into thepassageway 52 of the partially threaded member 27. Toward the distal end50, the outer surface of the partially threaded member 27 forms anannularly shaped groove 58. The outer surface of the partially threadedmember 27 also forms a tapered surface 60, located distally adjacent tothe annularly shaped groove 58, toward the distal end 50. A pointedannular tip 61 forms the distal end 50 of the partially threaded member27.

With reference to FIGS. 5A and 5B, the rotator handle 28 preferablycomprises an elongated cylinder having a proximal end 62 and a distalend 63 and includes a passageway 64 extending longitudinallytherethrough. On its outer surface, the rotator handle 28 includesgrooved portions 66 extending along its length. On its inner surface,the rotator handle 28 includes a threaded portion 68 that extendsinwardly from the distal end 63, a first annularly shaped recess 70proximally adjacent the threaded portion 68, an annular flange 72adjacent the first annularly shaped recess 70 extending inwardly fromthe inner surface, and a second annularly shaped recess 74 adjacent theproximal end 62 of the rotator handle 28. Fastener openings 75 pass fromthe outer surface to the inner surface of the rotator handle 28 in thearea of the passageway 64 located proximally adjacent the secondannularly shaped recess 74 distally adjacent the proximal end 62 of therotator handle 28. An access opening 76 passes from the outer surface tothe inner surface of the rotator handle 28 in the area of the passageway64 distally adjacent the second annularly shaped recess 74 andproximally adjacent the annularly shaped flange 72. A second accessopening 77 also extends from the outer surface to the inner surface ofthe rotator handle 28 at a proximal end of the threaded portion 68.

With reference to FIGS. 6A and 6B, the second core member 29 isgenerally tube shaped and includes a passageway 78 extendingtherethrough. A flat portion 80 of the second core member 29 furtherdefines its outer surface. The outer surface of the second core member29 includes a slot 82 which travels longitudinally along its length. Thesecond core member 29 also includes a longitudinally extending slot 84passing through the flat portion 80 of the outer surface into thepassageway 78 of the second core member 29.

With reference to FIGS. 7A and 7B, the hub 30 is formed by first andsecond cylindrical sections 85, 86 connected by a tapered section 87. Apassageway 88 extends through the hub 30. The passageway 88 increases insize in the tapered section 87 while transitioning from the firstcylindrical section 85 to the second cylindrical section 86. Ahemostasis valve opening 90 extends diagonally from an outer surface ofthe second cylindrical section 86 to an inner surface thereof. At aproximal end 92 of the hub 30, the inner surface includes an annularlyshaped principal recess 94 that forms a shoulder at a proximal end ofthe passageway 88. Additional semi-cylindrical recesses 96 are locatedaround the circumference of the annularly shaped principal recess 94. Asecond annularly shaped recess 98 extends around the inner surface ofthe hub 30 in the area in which the semi-cylindrical recesses 96 arelocated, leaving individual flanges 100 extending radially inwardlyalong the inner surface at the proximal end 92 of the hub 30.

The guide tube 32, shown in FIG. 8, is tube shaped and has a passagewayextending longitudinally therethrough. A proximal section 110 and adistal section 112 are both straight and form an angled relation to eachother. A transition section 113 is curved and connects the proximal anddistal sections 110, 112.

The component parts of the handle 22 are preferably assembled as shownin FIG. 2. A first thrust washer 114 is placed on the outer surface ofthe first core member 26 distally adjacent the flange 34 (see FIG. 3A)of the first core member 26, and the first core member 26 is insertedinto the rotator handle 28 through the proximal end 62 (see FIG. 5A) ofthe rotator handle 28. A second thrust washer 116 is placed proximal tothe proximal end 36 of the first core member 26. The first thrust washer114 is sandwiched between the annular flange 72 of the rotator handle 28and the flange 34 of the first core member 26. The flange 34 sits in thearea between the annularly shaped flange 72 and the second annularlyshaped recess 74 of the rotator handle 28. A snap ring 118 is placed inthe second annularly shaped recess 74 (see FIG. 5B) and contacts thesecond thrust washer 116, thus retaining the position of the first coremember 26.

A first core member fastener (not shown) engages the first fasteneropening 44 (see FIG. 3B) of the first core member 26. A ball bearing 122is placed in the first fastener opening 44. The access opening 76 (seeFIG. 5B) of the rotator handle 28 allows for access to the first coremember fastener.

The partially threaded member 27 is screwed into the rotator handle 28from the distal end 63 of the rotator handle 28. The exterior thread 54of the partially threaded member 27 engages the threaded portion 68 ofinner surface of the rotator handle 28. The first core member 26 sitsinside the passageway 52 of the partially threaded member 27. When thepartially threaded member 27 is fully engaged within the rotator handle28 as shown in FIG. 2, the proximal end 48 of the partially threadedmember 27 abuts the annularly shaped flange 72 of the rotator handle 28.

A dowel 124 engages the dowel opening 56 of the partially threadedmember 27 (see FIG. 4B) and extends from the outer surface of thepartially threaded member 27 into the first slot opening 38 of the firstcore member 26. When the partially threaded member 27 is fully engagedin the rotator handle 28, the dowel 124 is located in the area of thepassageway 64 of the rotator handle 28 corresponding to the firstannularly shaped recess 70 (see FIG. 5B). The dowel 124 is placed intothe dowel opening 56 of the partially threaded member 27 through thesecond access opening 77 of the rotator handle 28 as the partiallythreaded member 27 is screwed into the rotator handle 28 and the dowelopening 56, second access opening 77, and first slot opening 38 of thefirst core member 26 are aligned.

The end cap 23 is secured to the proximal end 62 of the rotator handle28. The end cap 23 includes a cylindrically shaped first contact surface126 which contacts the inner surface of the rotator handle 28 and asecond contact surface 128 which contacts the proximal end 62 of therotator handle 28. A passageway 130 extends through the end cap 23 andis placed in communication with the passageway 64 of the rotator handle28. The first contact surface 126 of the end cap 23 is aligned with thefastener openings 75 of the rotator handle 28. Set screws (not shown)engage the fastener openings 75 to secure the end cap 23 to the rotatorhandle 28.

The second core member 29 is placed in the passageway 88 of the hub 30.The slot opening 84 (see FIG. 6B) of the second core member 29 isaligned with the hemostasis valve opening 90 (see FIG. 7B) of the hub30. A slab 134 is placed in the annularly shaped principal recess 94 ofthe hub 30 proximally adjacent to the second core member 29. The slab134 is preferably formed of polyisoprene, and includes a central opening136 placed in communication with the passageway 88 of the second coremember 29 as well as a guide tube opening 138 which is placed incommunication with the slot 82 of the second core member 29. The slab126 can be adhered to the inner surface of the hub 30.

The proximal section 110 (see FIG. 8) of the guide tube 32 is insertedinto the slot 40 of the first core member 26. The guide tube 32 passesthrough the slab 134. The distal section 112 of the guide tube 32 isinserted into the slot 82 of the second core member 29.

The pointed annular tip 61 (see FIG. 4B) of the partially threadedmember 27 is pressed into the slab 134, and the individual flanges 100(see FIG. 7A) at the proximal end 92 of the hub 30 engage in theannularly shaped groove 58 of the partially threaded member 27 toconnect the hub 30 to the partially threaded member 27. The flanges 100ride along the tapered surface 60 of the partially threaded member 27before engaging the annularly shaped groove 58 of the partially threadedmember 27. Upon assembly between the partially threaded member 27 andthe hub 30, and when the partially threaded member 27 is fully engagedin the rotator handle 28, the proximal end 92 of the hub 30 abuts therotator handle 28. Further, as shown in FIG. 2, the center section 113of the guide tube 32 passes through the slab 134.

With reference to FIG. 9, the sleeve 19 is preferably an elongatetubular structure formed with a center lumen 139 and first and secondouter lumens 140, 141. The sleeve includes a proximal end 142 and adistal end 143, an outer surface 144, and an inner surface 145. Thesleeve 20 may be formed from any suitable material, but preferably ismade of thermoplastic elastomers formed from polyether block amides,commercially available as Pebax®. Toward the distal end 143, the sleeve19 includes a soft durometer section capable of flexing. The softdurometer section of the sleeve 19 is preferably made of 55D Pebax®, andis capable of flexing, as described below. A remaining portion of thesleeve 19 is preferably made of 72D Pebax®, which is more stiff than 55DPebax®. The stiffness of 72D Pebax prevents the sleeve from excessivebending, thus giving the operator the ability to push the deliverysystem 10 through the potentially constricting body vessel, and allowingthe delivery system 10 to more effectively track to the native valvesite, as described below. The sleeve 19 can also be formed of wire braidanywhere along the length thereof. Wire braid can also contribute to thestiffness and pushability of the delivery system 10.

With reference to FIG. 10, the steerable section 20 of the deliverysleeve assembly is shown in cross section. The steerable sectiongenerally includes a flex tube 146 and a cover 148. The flex tube 146 ispreferably tube shaped, having an inner surface 150, an outer surface152, and a passageway 154 extending therethrough. The flex tube 146 isfurther defined by a proximal end 156, a center section 158, and adistal end 160. With reference to FIG. 11, a plurality of v-shapednotches 162 are provided, such as by laser cutting, in the flex tube 146adjacent the proximal end 156. The notches 162 are shaped to providepointed barbs 164. Along the center section 158 of the flex tube 146,circumferentially extending elongate openings 166 are provided. Eachelongate opening 166 preferably includes two elongate portions 168connected by a curved portion 170. Circular portions 172 are provided atthe ends of the elongate openings. Tube portions 174 remainsubstantially intact and will be described in more detail below. A notch176 is formed at the distal end 160 of the flex tube 146. In onepreferred embodiment, the flex tube 146 is made of a stainless steelhypo-tube.

With reference again to FIG. 10, the cover 148 is preferablytube-shaped, having proximal and distal ends 178, 180, and including anouter surface 182 and an inner surface 184, with a passageway 186extending longitudinally therethrough. In a preferred embodiment, thecover 148 is formed of soft durometer material such as 55D Pebax®. Thesoft durometer 55D Pebax® of the cover 148 allows it to stretch andflex, as described below.

The steerable section 20 is assembled by placing the flex tube 146inside the cover 148. The cover 148 may be stretched prior to assemblyto give the steerable section 20 desirable features, as outlined below.The outer surface of the flex tube 146 contacts the inner surface of thecover 148. The proximal end 178 of the cover 148 extends proximally fromthe proximal end 156 of the flex tube 146, and the distal end 180 of thecover 148 extends distally from the distal end 160 of the flex tube 146.

With reference to FIG. 12, an alternative embodiment of the steerablesection 20 includes a connector 188 having a proximal end 190 and adistal end 192. The connector 188 is tube shaped, having a passageway194 longitudinally extending therethrough. An annularly shaped flange196 protrudes from an inner surface 198 of the connector 188.

To assemble the alternative embodiment of the steerable section 20including the connector 188, the proximal end 156 of the flex tube 146is inserted into the passageway 194 of the connector 188 until it abutsthe annularly shaped flange 196. The outer surface 152 of the flex tube146 contacts the inner surface 198 of the connector 188, and can beadhered thereto using adhesion. The cover 148 is placed over the flextube 146 and the connector 188. The proximal end 190 of the connector188 extends proximally from the proximal end 178 of the cover 148, andthe distal end 180 of the cover 148 extends distally from the distal end160 of the flex tube 146 (see FIG. 10).

With reference to FIG. 13, the shroud section 21 is shown incross-section. The shroud section 21 generally includes a shroud 200 anda ring 202. With reference to FIGS. 14A and 14B, the shroud 200 ispreferably cylindrical-shaped and comprises three continuous cylindricalsections: a rim 204 near a proximal end 206, a main body 208 near adistal end 210, and a neck 212 located therebetween. A passageway 213extends through the shroud 200, which includes an inner surface 216 andan outer surface 218. Slots 214 run from the proximal end 210 of theshroud 200 into the neck 212. The neck 212 has a smaller circumferencethan the rim 204 and the main body 208, resulting in a groove 220 alongthe outer surface 218 of the shroud 200.

With reference now to FIGS. 15A through 15C, the ring 202 has a proximalend 222, a distal end 224 and a passageway 225 extending longitudinallytherethrough. The ring 202 includes a proximal outer surface 226, adistal outer surface 228, and an inner surface 230. An outer face 232runs perpendicular to the proximal and distal outer surfaces 226, 228 ofthe ring 202 and connects the proximal and distal outer surfaces 226,228, which generally run parallel to one another. The inner surface 230includes an angled surface 234 toward the distal end 224, causing thepassageway 225 of the ring to increase in diameter near the distal end224 of the ring 202.

A slot 236 extends into the distal end of the ring 202 and through thedistal outer surface 228 to the inner surface 230 and parallel to acentral axis of the ring 202, creating a slot face 238 opposed to theouter face 232. A first lumen 240 and a second lumen 242 extend from theslot face 238 to the outer face 232 of the ring 202. The proximal outersurface 226 also includes a first semi-cylindrical recess 244 and asecond semi-cylindrical recess 246 which run parallel to the centralaxis of the ring 202 and pass from the proximal end 222 to the outerface 232 of the ring 202. The first cylindrical recess 244 is alignedwith the first lumen 240, and the second cylindrical recess 246 isaligned with the second lumen 242.

The shroud section 21 is formed by inserting the proximal end of theshroud 200 into the ring 202 according to FIG. 13. The rim 204 flexes topermit this. The ring 202 fits snugly in the groove 220 (see FIG. 14B),such that the inner surface 230 and the proximal and distal ends 222,224 of the ring 202 (see FIG. 15A) contact the outer surface 218 of theshroud 200. The ring 202 is situated so that either of the slots 214 ofthe shroud 200 (see FIG. 14A) is aligned with the slot 236 of the ring202.

With reference to FIG. 16, the balloon catheter 15 includes a tubesection 16 and a support 17. The tube section 16 includes a guidewireshaft 248, a balloon shaft 250, both of which are connected to thesupport 17, and a balloon 252. The guidewire shaft 248 having a proximalend 256 and a distal end 258 includes an inner surface 260, an outersurface 262, and a passageway 264 longitudinally extending therethrough.The guidewire shaft 248 can be formed of nylon, braided stainless steelwires, or Pebax® at differing portions along its length, according tothe need for rigidity and flexibility. Teflon® can be used to form theinner surface 260 of the guidewire shaft 248. The balloon shaft 250having a proximal end 266 and a distal end 268 includes an inner surface270, an outer surface 272, and a passageway 274 longitudinally extendingtherethrough. The balloon shaft 250 can be formed of any combination ofnylon, Pebax®, or braided stainless steel wires at differing portionsalong its length, according to the need for rigidity and flexibility.

With reference now to FIGS. 17A and 17B, the balloon 252 has a proximalend 276 and a distal end 278 includes an inner surface 280, an outersurface 282, and a passageway 284 extending longitudinally therethrough.When viewed from the proximal end 276 to the distal end 278, the balloon252 includes five portions: a first slender portion 286, a first coneportion 288, a main cylindrical portion 290, a second cone portion 292,and a second slender portion 294. The balloon 252 can be formed ofnylon, and is rated at a burst pressure of 6-8 atm. In preferredembodiments, the expanded diameter of the balloon ranges from about 20to 28 mm and, more preferably, is about 23 mm.

With reference again to FIG. 16, the support 17 includes a wire inletopening 296, an fluid inlet opening 298, and a main shaft opening 300.The wire inlet opening 296 includes an interior surface 302, and themain shaft opening 300 likewise includes an interior surface 304. Theopenings 296, 298, 300 are arranged so as to be in communication withone another.

The balloon catheter 15 is assembled as shown in FIG. 16. The guidewireshaft 248 is inserted into the main shaft opening 300. The proximal endof the guidewire shaft 248 is placed in the wire inlet opening 296, andthe outer surface 262 of the guidewire shaft 248 is secured to theinterior surface 302 of the wire inlet opening 296, for example, byadhesion. The guidewire shaft 248 is of a smaller diameter than the mainshaft opening 300 and as such, does not contact the interior surface 304of the main shaft opening 300.

The balloon shaft 250 is placed over the guidewire shaft 248. Theproximal end 266 of the balloon shaft 250 is placed in the main shaftopening 300 of the support 17, and the outer surface 272 of the balloonshaft 250 is secured to the interior surface 304 of the main shaftopening 300. As shown in FIG. 16, the guidewire shaft 248 is of asmaller diameter than the balloon shaft 250, and the outer surface 262of the guidewire shaft 248 does not contact the inner surface 270 of theballoon shaft 250 to permit air flow.

The proximal end 256 of the guidewire shaft 248 extends proximally fromthe proximal end 266 of the balloon shaft 250, and the distal end 258 ofthe guidewire shaft extends distally from the distal end 268 of theballoon shaft 250.

The proximal end 276 of the balloon 252 is placed over the distal end268 of the balloon shaft 250. The inner surface 280 of the balloon 252in the area of the first slender portion 286 is secured to the outersurface 272 of the balloon shaft 250. The distal end 278 of the balloon252 is placed over the distal end 258 of the guidewire shaft 248. Theinner surface 280 of the balloon 252 in the area of the second slenderportion 294 is secured to the outer surface 262 of the guidewire shaft248. The balloon 252 can secured to the balloon shaft 250 and theguidewire shaft 248 by a process involving the curing of adhesive withultraviolet light or laser welding.

First and second marker bands 306, 308 are placed along the guidewireshaft 248 within the passageway 284 of the balloon 252. The marker bands306, 308 can be secured to the outer surface 262 of the guidewire shaft248 by an adhesive or swaging. The position of the first marker band 306roughly corresponds to the transition between the first cone portion 288and the main cylindrical portion 290 of the balloon 252 (see FIG. 17B).The position of the second marker band 308 roughly corresponds to thetransition between the main cylindrical portion 290 and the second coneportion 292 of the balloon 252 (see FIG. 17B). The marker bands 306, 308can be formed of 90 percent platinum and 10 percent iridium in order toindicate by fluoroscopy, a process known in the art, the position of theballoon catheter 19 within the patient. A soft tip 310 located distallyfrom the balloon 252 is placed over the distal end 258 of the guidewireshaft 248.

The delivery sleeve assembly 18 is formed by joining the sleeve 19 andsteerable section 20. The distal end 143 of the sleeve 19 is insertedinto the passageway 186 of the cover 148 and the passageway 154 of theflex tube 146 as shown in FIG. 10. The sleeve 19 is positioned relativeto the steerable section 16 such that the first and second outer lumens140, 141 are aligned with the curved portions 170 of the elongateopenings 166 of the flex tube 146. The outer surface 144 of the sleeve19 is secured to the inner surface 150 of the flex tube 146, forexample, by thermal or adhesive joining. Further, the barbs 164 mayengage the distal end 143 of the sleeve 19 to make the connection. Theinner surface 184 of the cover 148 is also secured to the outer surface144 of the sleeve 19 at the proximal end 178 of the cover 148 byadhesive or by thermal joining.

In the alternative embodiment (see FIG. 12) involving the connector 188,the outer surface 144 of the sleeve 19 is secured at its distal end 143to the inner surface 198 of the connector 188 toward the proximal end190 of the connector 188. The distal end 143 of the sleeve 19 abuts theannularly shaped flange 196 of the connector 188.

The shroud section 21 is also joined to the steerable section 20 to formthe delivery sleeve assembly 18 (see FIG. 10). The proximal end 206 ofthe shroud 200 is inserted into the passageway 186 of the cover 148 atthe distal end 180 of the cover 148. The proximal end 206 of the shroud200 is further inserted into the passageway 154 of the flex tube 146 atthe distal end 160 of the flex tube 146. The slot 214 of the shroud 200is aligned with the notch 176 of the flex tube 146 (see also FIGS. 11and 14A).

The outer surface 218 of the shroud 200 in the area of the rim 204 issecured to the inner surface 150 of the flex tube 146. The proximalouter surface 226 of the ring 202 is secured to the inner surface 150 ofthe flex tube 146 adjacent the distal end 160 of the flex tube 146. Thedistal end 160 of the flex tube 146 abuts the outer face 232 of the ring202. The shroud section 21 can be secured to the flex tube 146 withmechanical bond and adhesive.

The inner surface 184 of the cover 148 is secured to the distal outersurface 228 of the ring 202. The inner surface 184 of the cover 148 isalso secured to the outer surface 218 of the shroud 200 in the area ofthe main body 208. These connections can be made by adhesive or thermaljoining, or both. The main body 208 of the shroud 200 extends distallyfrom the distal end 180 of the cover 148.

The delivery sleeve assembly 18 is connected to the handle 22 as theproximal end 142 of the sleeve 19 is inserted into the passageway 88 ofthe hub 30 and the outer surface 144 of the sleeve 19 is secured to theinner surface of the hub 30, for example, by an adhesive.

A pull wire 312 shown in FIG. 2 is inserted into the delivery system 10.A first end of the pull wire 312 is placed in the first fastener opening44 of the first core member 26. The first core member fastener (notshown) bears upon ball bearing 122, which secures the pull wire 312 inthe first fastener opening 44. The pull wire 312 passes through thelongitudinally extending access opening 46 (see FIG. 3B) of the firstcore member 26. The pull wire 312 passes through the passageway of theguide tube 32 which is located in the slot 40 of the first core member26, the guide tube opening 138 of the slab 134, and the slot 82 of thesecond core member 29, and then through the passageway 88 of the hub 30.The pull wire 312 then passes through the first lumen 140 of the sleeve19 (see FIG. 9). The pull wire 312 exits the sleeve 19 and passesthrough the passageway 154 of the flex tube 146 (see FIG. 10). The pullwire 312 passes through the first semi-cylindrical recess 244 and thefirst lumen 240 of the ring 202. The pull wire 312 is strung against theslot face 238 of the ring 202. The pull wire 312 is then returnedthrough the second lumen 242 and the second semi-cylindrical recess 246of the ring 202. The pull wire 312 passes again through the passageway154 of the flex tube 146. The pull wire 312 passes through the secondouter lumen 141 of the delivery sleeve 19, through the passageway 88 ofthe hub 30 (again), through the passageway of the guide tube 32 (again),and through the access opening 46 of the slot 40 of the first coremember 26. A second end of the pull wire 312 is secured to the firstcore member 26 by pressure exerted by the first core member fastener(not shown) on the ball bearing 122, which secures the pull wire 312.The pull wire 312 can be formed of nitinol or stainless steel.

With reference now to FIGS. 1 and 16, a preferred method of using theheart valve delivery system 10 will now be described in more detail. Thedevices and methods disclosed herein are particularly well-suited forreplacing a stenotic aortic valve. Those skilled in the art willrecognize that it may be necessary to pre-dilate the leaflets of thestenotic aortic valve before deploying a prosthetic valve within theaortic valve. Pre-dilation increases the flow area through the aorticvalve and creates an opening in the leaflets of sufficient size toreceive the prosthetic valve. Pre-dilatation is preferably achievedusing an expandable member, such as a dilatation balloon catheter.Additional details regarding pre-dilatation and valve replacement can befound in Applicant's co-pending application Ser. No. 10/139,741, filedMay 2, 2002.

The assembly and operation of the heart valve delivery system 10 willnow be described. During assembly, the balloon catheter 15 is insertedinto the opening created by the assembly of the handle 22 and thedelivery sleeve assembly 18. The support 17 of the balloon catheter 15is located proximally to the handle 22. The balloon shaft 250, and theguidewire shaft 248, pass through the passageway 130 of the end cap 23(see FIG. 2), the passageway 33 of the first core member 26, the centralopening 136 of the slab 134, the passageway 78 of the second core member29, the passageway 88 of the hub 30, the central lumen 139 of the sleeve19, and the passageway 154 of the flex tube 146. The balloon shaft 250passes into the passageway 213 of the shroud 200 according to FIG. 18A,while the guidewire shaft 248 passes through the passageway 213 of theshroud 200. The proximal end 276 of the balloon 252 is located in thepassageway 213 of the shroud 200, and the balloon 252 extends distallyfrom the distal end 210 of the shroud 200.

The prosthetic valve 11 is mounted onto the main cylindrical portion 290of the balloon 252, distally from the distal end 210 of the shroud 200,as shown in FIG. 18A. The valve 11 is known in the art and iscollapsible to a first position over the balloon 252, as shown inFIG. 1. Alternatively, the valve 11 can be mounted on the balloon 252and placed inside the shroud 200, as shown in FIG. 18B.

The valve 11 can take a variety of different forms. In preferredembodiments, the valve generally comprises an expandable stent portionthat supports a valve structure. The stent portion has sufficient radialstrength to hold the valve at the treatment site and resist recoil ofthe stenotic valve leaflets. Additional details regarding preferredballoon expandable valve embodiments can be found in Applicant's U.S.Pat. Nos. 6,730,118 and 6,893,460, each entitled IMPLANTABLE PROSTHETICVALVE, which are incorporated by reference herein. It will also beappreciated that the delivery system may be used with self-expandingprosthetic valves. For example, when using a self-expanding valve, apusher may be substituted for the balloon catheter for ejecting theself-expanding valve from the delivery sleeve assembly.

With continued reference to the illustrated embodiment, the guide wire14 is placed in the passageway 264 of the guidewire shaft 248 such thatit extends distally from the distal end 258 of the guidewire shaft 248and proximally from the wire inlet opening 296 of the support 17 of theballoon catheter 15. The process of inserting a catheter into the humanbody for tracking is known in the art, e.g. by U.S. Pat. No. 5,968,068entitled ENDOVASCULAR DELIVERY SYSTEM, which is incorporated byreference herein.

The guide wire 14 is placed in the body through a dilator (not shown)which expands the inner diameter of the body vessel in order tointroduce an introducer sheath assembly 400, shown in FIG. 19, over theguide wire 14. Preferred dilator diameters range between 12 and 22French. The introducer sheath assembly 400 includes an introducer sleeve402 and an introducer housing 404 attached to a proximal end of theintroducer sleeve 402. Introducer sheath assembly diameters of 22 or 24French are preferred.

A series of valves are located inside the introducer housing 404. On aproximal end of the introducer housing 404, an end piece 406 isattached, the end piece having an opening extending into the introducerhousing 404 in the area of the series of valves, and a ridge 408 facinga distal end of the introducer housing 404. The introducer sleeve 402extends into the body vessel, with the introducer housing 404 locatedoutside the body vessel on a proximal end on a proximal end of theintroducer sleeve 402. In a preferred embodiment, the introducer sleeve402 is coated with a hydrophilic coating and extends into the bodyvessel about 9 inches, just past the iliac bifurcation and into theabdominal aorta of the patient. The introducer sheath assembly 400provides a mechanism for advancing the prosthetic valve into the aortain a safe and effective manner.

With reference to FIG. 20, a loader assembly 500 includes a loader 502,a loader cap 504, and a loader seal 506. The loader 502 is tube shaped,having exterior threading 508 at a proximal end for connection with theloader cap 504. The loader 502 includes flexible flanges 510 extendingparallel thereto and having snap ridges 512 facing the proximal end ofthe loader 502. The loader cap 504 includes a loader cap opening 514 ina proximal end thereof and a threaded inner surface 516 for engagementwith the exterior threading 508 of the loader 502. The loader seal 506is secured to the loader cap 504, and a loader seal opening 518 isaligned with the loader cap opening 514.

With reference to FIG. 21A, the loader cap 504 and loader seal 506 arepassed onto the delivery system 10 as the sleeve 19 engages the loadercap opening 514 and loader seal opening 518. The distal end of thedelivery system 10, passing over the guide wire 14, is inserted into theproximal end of the loader 502, as shown in FIG. 21B. The loader cap 504screws onto the proximal end of the loader 502.

With reference to FIG. 22, the flexible flanges 510 of the loader 502snap into the end piece 406 of the introducer housing 404. In thisposition, the ridge 408 of the end piece 406 bears against the snapridge 512 of the flexible flanges 510, and the loader 502 passes throughthe series of valves located inside the introducer housing 404, thusplacing the delivery system 10 in communication with an inner passagewayof the introducer sheath and thus, with the body vessel. The loaderassembly 500 advantageously allows the introduction of the deliverysystem 10 into the introducer sheath assembly 400 without substantialblood loss from the patient.

The prosthetic valve 11, balloon catheter 15 and delivery sleeveassembly 18 are advanced over the guide wire 14 through the introducersheath, preferably as single unit, while tracking through the bodyvessel to the native valve site (see FIG. 1). In one advantageousfeature, the delivery system 10 provides excellent pushability forfacilitating advancement of the prosthetic valve 11 through theintroducer sheath. In one embodiment, the delivery system 10 providessufficient pushability to push through an introducer sheath having aninner circumference that is 2 French size smaller than outercircumferences of the valve 11 or shroud 200.

As the prosthetic valve 11 reaches the aortic arch 13 as shown in FIG.1, the steerable function of the delivery system 10, described below, isactuated for facilitating advancement of the valve 11 around the arch.More particularly, the bending of the steerable section 20 assists insteering the valve 11 and/or the distal end 210 of the shroud 200 (seeFIG. 14A) away from the inner surface of the aortic arch 13. As aresult, retrograde advancement of the valve 11 around the aortic arch 13may be achieved without damaging the aorta 13 or the valve 11. In onepreferred delivery method, the valve is advanced over the aortic archwith little or no contact between the valve and the aorta.

In the illustrated embodiment, the steerable function of the deliverysystem 10 is accomplished as the operator rotates the rotator handle 28(see FIG. 2). As the rotator handle 28 is rotated, the threaded portion68 acts in conjunction with the exterior thread 54 of the partiallythreaded member 27 (see FIG. 4A), which does not rotate. The rotatorhandle 28 thus moves linearly relative to the partially threaded member27. The first core member 26 also moves linearly relative to thepartially threaded member 27 (see FIG. 2). The dowel 124 preventsrelative rotation between the first core member 26 and the partiallythreaded member 27.

As the first core member 26 moves distally from the partially threadedmember 27, the pull wire 312, connected to the first core member 26 bythe ball bearing 122, exerts a force on the slot face 238 of the ring202 (see FIG. 15A). The pull wire 312 draws the ring 202 toward thehandle 22. The side of the delivery system 10 along which the pull wire312 passes bends along the steerable section 20 as the elongate openings166 of the flex tube 146 converge (see FIG. 11). The steerable section20 bends until the pressure in the pull wire 312 is relieved. Additionalrotation of the rotator handle 28 thus results in additional bending.The friction between the threaded portion 68 of the rotator handle 28and the exterior thread 54 of the partially threaded member 27 (seeFIGS. 4A and 5B) is sufficient to hold the pull wire 312 taut, thuspreserving the shape of the bend in the steerable section 20 when theoperator releases the rotator handle 28.

The natural rigidity of the cover 148 (see FIG. 10), as well as thenatural rigidity of the balloon catheter 15 (see FIG. 16), act againstthe bending of the steerable section 20. The force on the pull wire 312bends the steerable section 20, while the rigidity of the cover 148 andballoon catheter 15 described above resists the bending, thus “locking”the delivery system 10 in place over a range of positions from straightto fully curved, according to the rotation of the rotator handle 28. Thecover 148 also protects the body vessel from the flex tube 146 (see FIG.10), which absent the cover 148, may scrape or otherwise lacerate thebody vessel.

As the balloon catheter 15 is advanced to the native valve site, theoperator uses the marker bands 306, 308 (see FIG. 16) to identify thelocation of the valve 20, according to the process of fluoroscopy, whichis well known in the art. The operator can adjust the position of thevalve 11 by actuating the rotator handle 28 while holding the hub 30stationary (see FIG. 2). Further control over valve position can beachieved by twisting the hub 30. The sleeve 19 is attached to the hub30, and the delivery system 10 is sufficiently rigid to transmit thetwisting movement to the distal end. Twisting motion is transferredthrough the steerable section 20 when the tube portions 174 of the flextube 146 contact one another (see FIG. 11). Such contact can occur whenthe flex tube is fully bent, or can occur during twisting as the curvedportions 170 of the elongate opening close such that the tube portions174 contact one another.

The delivery sleeve assembly 18 (see FIG. 1) is at its most rigid whenall of the remaining tube portions 174 of the flex tube 148 (see FIG.11) are in contact with one another and the steerable section 20 isfully curved. In this position, the shape of the steerable section 20preferably corresponds closely to the shape of the aortic arch 13 (asshown in FIG. 1) for ease of tracking. When pushing across the stenoticleaflets 12, the steerable section 20 is located in the ascending aortaof the patient, and the soft durometer section of the sleeve 19 flexesand bears against the aortic arch 13 (see FIG. 1), thereby preventingdamage to the inner wall of the aorta.

After the delivery system 10 has been advanced such that the valve 11 islocated adjacent to the native valve, the balloon catheter 15 may bedistally advanced relative to the delivery sleeve assembly 18 to betterposition the valve 11 within the native leaflets. To accomplish this,the balloon catheter 15 is slidably advanced through the sleeve 19 andsteerable section 20. In another advantageous feature, the deliverysleeve assembly 18 advantageously allows the physician to adjust thecurvature of the steerable section 20 for properly aligning theprosthetic valve 11 with respect to the native valve. As a result, whenthe balloon catheter 15 is advanced distally, the prosthetic valveadvances into the center of the native valve. Furthermore, the deliverysystem 10 provides sufficient pushability to push the balloon catheter15 and valve 11 across the stenotic leaflets 12, or alternatively, topush the balloon catheter 15 across the stenotic leaflets 12. The shroud200 (see FIG. 14A) may also cross the stenotic leaflets 12 during thisprocess.

Once the stenotic leaflets 12 have been pushed away, the delivery system10 deploys the valve 11 in the native valve site, as shown in FIG. 23.The soft durometer section of the sleeve 19 bears against the aorticarch 13, while the steerable section 20 passes through the ascendingaorta and is adjusted to position the valve 11. The valve 11 is balloonexpandable and once positioned, the balloon 252 is inflated to securethe position of the valve 11 in the native valve site. The balloon 252is then deflated, and the entire delivery system 10 is withdrawn as itpasses back over the guide wire 14, and exits the body vasculaturethrough the introducer sheath. The guide wire 14 is then withdrawn,followed by the introducer sheath.

In the alternative embodiment of the invention, wherein the valve 11 isplaced inside the shroud 200, the delivery sleeve assembly 18 (seeFIG. 1) is retracted once the valve 11 has reached the native valvesite. The delivery sleeve assembly 18 is retracted as the operator holdsthe support 17 steady and pulls back (proximally) on the handle 22,which causes the delivery sleeve assembly 18 to retract proximally,exposing the valve 11 to the native valve site and allowing the balloon252 to inflate as shown in FIG. 23, and thus deploy the valve 11 asdescribed above.

It will be appreciated that embodiments of the heart valve deliverysystem 10 provide improved devices and methods for advancing aprosthetic heart valve through a patient's vasculature. In one preferredembodiment, the cooperation of components described herein allows anuncovered prosthetic valve to be advanced through the patient'svasculature and around the aortic arch in a safe manner. Accordingly,the delivery system enables advancement of a prosthetic valve around theaortic arch without requiring the introduction of an outer sheath intothe aortic arch. This is an advantageous feature because the use of asheath would increase the diameter of the delivery system, therebycomplicating the delivery of the valve. In addition to providing animproved steering mechanism for navigating the aortic arch withoutdamaging the inner wall of the aorta, it will be appreciated by thoseskilled in the art that the delivery system provides excellentpushability such that the physician has excellent control over themovement and location of the prosthetic valve during advancement intothe native valve. This feature is particularly advantageous whentraversing stenotic valve leaflets. Accordingly, embodiments of thepresent invention provide an improved delivery system for advancing aprosthetic valve to the site of a native aortic valve using a steerableassembly that eliminates the need for an outer sheath in the aorta,while providing sufficiently pushability to pass through narrowvasculature and/or stenotic valve leaflets. As a result, embodiments ofthe present invention provide improved devices and methods forpercutaneously advancing a balloon-expandable prosthetic valve to thesite of a stenotic aortic valve using a retrograde approach.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription and not of limitation. Therefore, changes may be made withinthe scope of the appended claims without departing from the true scopeand spirit of the invention.

1. A delivery system for deploying a prosthetic valve within a nativeaortic valve in a human heart, comprising: a tubular sleeve; aselectively steerable section permanently fixed to a distal end of thesleeve, the steerable section having a lumen with an inner diameter, thelumen communicating with an open distal end, the steerable sectionconstructed to have a greater flexibility than the tubular sleeve; apull wire permanently fixed to a distal end portion of the steerablesection for selectively controlling a curvature of the steerablesection, the steerable section capable of achieving sufficient curvatureto navigate around an aortic arch; an elongate balloon catheterextending through the sleeve and through the lumen of the steerablesection and out of the open distal end of the steerable section, theelongate balloon catheter being longitudinally movable relative to thesleeve and the steerable section; and a prosthetic valve disposed overan expandable balloon along a distal end portion of the elongate ballooncatheter, the prosthetic valve having an outer diameter larger than theinner diameter of the steerable section such that the prosthetic valveis prevented from moving proximally through the steerable section whenthe balloon is deflated and the prosthetic valve is in a radiallycompressed state on the deflated balloon, the prosthetic valvecomprising an expandable stent portion and a valve structure; whereinthe sleeve, steerable section, balloon catheter and prosthetic valve areconfigured for advancement as a single unit through a patient'svasculature while the prosthetic valve is positioned distal to thesteerable section and wherein the balloon catheter and prosthetic valveare movable in a distal direction relative to the sleeve and steerablesection for implanting the prosthetic valve within a native aorticvalve.
 2. The delivery system according to claim 1 wherein the sleevefurther comprises first and second outer lumens extending along a sideof the sleeve.
 3. The delivery system according to claim 2 wherein thepull wire passes through the first outer lumen, through the steerablesection to the distal end portion of the steerable section, and returnsthrough the steerable section and through the second outer lumen.
 4. Thedelivery system according to claim 1 wherein the steerable sectioncomprises a slotted tube having a first straight position and a secondcurved position.
 5. The delivery system according to claim 1 wherein thesleeve is formed of a polyether block amide and wherein the sleevecomprises a soft durometer polyether block amide near a distal endthereof.
 6. The delivery system according to claim 3 wherein the pullwire is actuated by a rotational handle assembly, wherein the rotationalhandle assembly is located proximal to the sleeve.
 7. The deliverysystem according to claim 1 wherein the distal end portion of thesteerable section abuts a proximal end of the prosthetic valve.
 8. Thedelivery system according to claim 1 further comprising a shroud coupledto the distal end portion of the steerable section and wherein theshroud surrounds at least a portion of the prosthetic valve duringadvancement through the patient's vasculature.
 9. The delivery systemaccording to claim 1, wherein the steerable section comprises a flexibletubular portion and a cover extending over at least a portion of thetubular portion, the cover being less flexible than the tubular portion.10. The delivery system of claim 1, wherein the pull wire has a proximalend portion connected to a handle mechanism, and a distal end portionconnected to the steerable section, and wherein actuating the handlemechanism is effective to move the pull wire proximally to bend thesteerable sector, while the sleeve undergoes substantially no deflectionfrom the pull wire.